1. Field of the Invention
This invention relates to a machine designed to repeatedly and accurately throw a football shaped object for catching practice, without the required assistance of a second person.
2. Prior Art
There have been numerous attempts to produce equipment capable of achieving repeatable, accurate football throws for use in catching practice. Designs by Dixon (U.S. Pat. Nos. 3,926,170, 3,951,125) and Meyer (U.S. Pat. No. 3,977,386) employed vertical and horizontal cantilever arms to simulate the arm motion of a quarterback. Centrifugal force and friction imparted the spinning effect required for stability during the ball flight. While these techniques may produce a throw, the equipment is large, bulky and can require significant effort to operate. Additionally, the ball spin that is required is imparted only indirectly as the ball rolls off of the carriage. This method is unlikely to produce the accuracy and consistency required for practical use.
Subsequently Paulson (U.S. Pat. No. 4,026,261) addressed the problem using a design with coacting or counter-rotating wheels powered by an electric motor to grip and fling the ball as it passes between the wheels. The wheels are slightly misaligned with one another, thus creating the spin required for a steady flight. This design likely produced more consistent flight characteristics and directly imparts the required spin on the ball. The disadvantages of this design include the large size and weight, the high cost of components and the requirement for high voltage alternating current power, which is frequently unavailable on a practice field. Also, the equipment did not have a method of throwing a ball to oneself, as an operator is required to aim and feed the ball into the equipment.
Several designs incorporate rubber bands as the means of propulsion. One method used large elastic bands as a slingshot (Dixon, U.S. Pat. No. 4,261,319) whereby the band is twisted to provide the ball spin at release. This design includes a timer for one person operation; however this design has the disadvantage of requiring a special football with a hole through the center. Adjustments to the throw distance, pulling back the elastic bands, and loading the football, all appear to be somewhat cumbersome. One other elastic band design for a shoulder launched mechanism (Ivy, U.S. Pat. No. 5,447,144) uses multiple elastic bands to provide propulsion to the ball. This design utilizes a torsion spring mechanism to impart spin to the ball at the end of the release stroke. Disadvantages of this design include the complexity of the assembly, likely high cost, and likelihood of being very cumbersome in practical use.
One design used an air cylinder and compressed air to propel a football (Sciarrillo, U.S. Pat. No. 5,224,701). This design uses the rapid extension of a pneumatic cylinder to provide propulsion. Spin is provided by mounting the inner shaft on a nut that spins down a rifled cage as the cylinder extends. The end of the shaft is contoured to contact the football which theoretically would spin along with it due to contact pressure. Disadvantages to this design are the size, weight and complexity of the equipment as well as the availability and expense of delivering high voltage power or compressed air to the place of use.
An additional pneumatic design (Sportfun—Mr. Quarterback Operation Manual, 2004) uses compressed air to launch a hollow plastic football from a portable launcher. This device is battery powered and portable, but has the disadvantage of requiring a custom, non regulation football and can best be described as a toy for children. It has a delay mechanism, however the timing varies only to the degree that the equipment requires more time to generate higher pressures for longer throws. Another toy design uses a motor and a rotating wheel to feed and propel a ball, however the patent clearly states the intent is for the toy market (Wojtkiewicz, U.S. Pat. No. 6,637,422).
Other inventors have added to the mechanisms for automatically feeding of balls into existing equipment (Osojnak, U.S. Pat. No. 4,723,532; Griffith, U.S. Pat. No. 4,596,230) as well as remotely controlling the release of a ball (Shultz et al., U.S. Pat. No. 6,679,239). These inventions are mentioned only to demonstrate the ongoing interest in equipment designed for the purpose of throwing footballs.